The invention relates, further, to an apparatus for operating a melt reduction process, with a blast furnace or with a melting assembly and at least one reduction assembly, batch materials being reducible by means of a reduction gas, using carbon carriers and, if appropriate, aggregates, and being meltable into pig iron or steel semifinished products, and the reacted reduction gas being divertible as top gas and, purified, if appropriate mixed with purified and cooled excess gas from the melting assembly, being dischargeable as export gas.
It is known from the prior art that process gases, such as, for example, top gas from melt reduction devices, or a mixture of residual gases are treated in other processes and plants, the thermal and chemical energy of the top gas often being utilized. Problems are a fluctuating gas composition and the low export gas pressure downstream of the scrubber systems, which make a more efficient treatment of the export gases difficult. Further, it is known that the export gas or pure top gas is employed in turbines for the generation of kinetic energy (expansion turbines) and heat (gas turbines). Here, too, there is the problem that, on account of the low pressure, the low calorific value after the admixture of residual gas from a CO2 removal plant and the calorific value fluctuations, the export gas can be used only in a disadvantageous way in a gas turbine or a combined-cycle power station.